It has been found that there is a need in the packaging industry for octagonal and rectangular shaped cartons that can be easily squared up on a pallet and that have easy locking bottom flanges or panels that are more resistant to tearing.
Locking mechanisms for closing the bottom of containers are well known in the packaging industry. In particular, bottom closure panels having combinations of notches and score lines have been used to provide many different variations of push-type end closure/locking mechanisms. See, for example, U.S. Pat. No. 3,539,090 to Blasdell, U.S. Pat. No. 3,101,882 to Parker, U.S. Pat. No. 2,361,603 to Cohen and U.S. Pat. No. 3,319,869 to Ostwald. The prior art devices attempt to solve the same general problem of closing and locking container bottom and/or top panels. However, each has a problem in utilization that makes it relatively unattractive to manufacture or use. For example, many of the prior art locking systems are not easily set up, have limited use dependent on the type and size of carton they are to be used on, and have problems with score memory or tearing of the flanges if not folded properly. In addition, many of the prior art locking mechanisms require added costs in materials or manufacture.
Accordingly, it is a broad object of this invention to provide an improved locking system for the bottom or top panels of a container or carton, which is inexpensive to produce, has application to a wide variety of cartons, and operates in a simple manner that allows a user to easily close and lock the end panels while reducing the risk of tearing and the negative effects of score memory.